Ever tried to do a head count of a milling crowd? Try, and you’ll realise why
people are often ordered to stay home during censuses of human populations.
And while some marine life will remain resident in one small area — of reef
or sheltered seagrass bed — many species migrate huge distances.

To get a handle on the nature of these mysterious undersea migrations in the
Pacific, Census scientists tagged some 4,300 marine predators from 23
different species, with extraordinary results.

Great white sharks were found to stick to precise patterns, some making the
5,000km journey from the Californian coast to